Inductive power coupling allows energy to be transferred from a power supply to an electric load without a wired connection therebetween. An oscillating electric potential is applied across a primary inductor. This sets up an oscillating magnetic field in the vicinity of the primary inductor. The oscillating magnetic field may induce a secondary oscillating electrical potential in a secondary inductor placed close to the primary inductor. In this way, electrical energy may be transmitted from the primary inductor to the secondary inductor by electromagnetic induction without a conductive connection between the inductors.
When electrical energy is transferred from a primary inductor to a secondary inductor, the inductors are said to be inductively coupled. An electric load wired in series with such a secondary inductor may draw energy from the power source wired to the primary inductor when the secondary inductor is inductively coupled thereto.
In order to control inductive power transfer between an inductive power outlet and an inductive power receiver various protocols have been suggested enabling regulation of power level and the like. For example, one such protocol is described in the applicants copending U.S. patent application Ser. No. 13/205,672 titled “Energy Efficient Inductive Power Transmission System and Method” which is incorporated herein by reference.
It is known in the art that inductive power transfer systems transfer AC electrical power at the resonant frequency of the inductive power transfer system. However, small fluctuations in the resonant frequency during power transmissions may result in substantive changes and losses in the transferred electrical power. Fluctuations in the inductive resonant frequency may be due changing environmental conditions or variations in alignment between primary inductive and secondary inductive coils.
Further, efficient inductive power transfer is only practical where the inductive receiver uses the same protocol as the inductive power outlet. Inductive receivers are generally configured to work in only according to one control protocol. However, because of the variety of protocols currently in use not all inductive receivers are compatible with all inductive power outlets.
Thus, there is a need in the art for an inductive power transfer system with a higher tolerance to environmental fluctuations and variations in inductive coil alignment and to low voltages transmissions, as well as a need in the art of an inductive power receiver operable to work according to multiple control protocols.